CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenue	$ 30,592	$ 18,422
Operating expenses
Cost of Revenue	9,732	4,899
Sales and marketing	11,236	8,531
General and administrative	15,436	10,009
Research and development	7,093	3,253
Amortization of intangibles assets	4,016	2,301
Impairment related and other	174
Total operating expenses	47,687	28,993
Operating income (loss)	(17,095)	(10,571)
Other income (loss), net	1,365	300
Interest income	19	86
Interest expense	(37)	(511)
Income (loss) before income taxes, equity loss and noncontrolling interest	(15,748)	(10,696)
Income tax (expense) benefit	(177)	(94)
Equity loss		(312)	[1]
Income (loss) from continuing operations	(15,925)	(11,102)
Income (loss) from discontinued operations, including gain on sale, net of tax		48
Net income (loss)	(15,925)	(11,054)
Less: Net income (loss) attributable to the noncontrolling interest	(1,160)	(904)
Net income (loss) attributable to Actua Corporation	(14,765)	(10,150)
Amounts attributable to Actua Corporation:
Net income (loss) from continuing operations	(14,765)	(10,198)
Net income (loss) from discontinued operations		48
Net income (loss) attributable to Actua Corporation	(14,765)	(10,150)
Basic income (loss) per share attributable to Actua Corporation:
Income (loss) from continuing operations	$ (0.40)	$ (0.27)
Income (loss) from discontinued operations		$ 0.00
Net income (loss)	$ (0.40)	$ (0.27)
Shares used in computation of basic income (loss) per share	36,842	37,096
Diluted income (loss) per share attributable to Actua Corporation:
Income (loss) from continuing operations	$ (0.40)	$ (0.27)
Income (loss) from discontinued operations		$ 0.00
Net income (loss)	$ (0.40)	$ (0.27)
Shares used in computation of diluted income (loss) per share	36,842	37,096
Net income (loss)	(15,925)	(11,054)
Other comprehensive income
Comprehensive income (loss)	(15,925)	(11,054)
Less: Comprehensive income (loss) attributable to noncontrolling interests	(1,160)	(904)
Comprehensive income (loss) attributable to Actua Corporation	$ (14,765)	$ (10,150)

[1] Includes Acquirgy, which ceased operations in 2015, and CIML, LLC (“CIML”), which ceased operations in 2014.